Phytic Acid Reduction by Bioprocessing as a Tool to Improve the in Vitro Digestibility of Faba Bean Protein

In legumes such as faba bean, phytic acid can form very stable complexes with proteins, thus hindering their accessibility for gastrointestinal digestion. This study was set up to investigate the influence of enzymatic phytase treatment and lactic acid bacteria fermentation (Lactobacillus plantarum VTT E-78076) on phytic acid reduction as well as on the protein quality and digestibility of faba bean flour. The soluble protein and release of free amino acids from faba bean flours were followed during a simulated in vitro digestion process. Phytase treatment efficiently reduced the amount of phytic acid in faba bean flour up to 89% degradation. The reduction of phytic acid content caused a shift in the protein solubility curve, showing higher solubility levels at low pH. Further, the enzyme-aided degradation of phytic acid considerably enhanced the digestibility of faba bean proteins (dose-dependent) and the release of free amino nitrogen in the first stage of digestion (gastric phase). The results propose the benefits of phytase treatment in plant-based foods where the phytic acid content may hinder the digestion of protein.